This invention pertains to continuous loop tape cartridges and, more particularly, to improvements in fast forward drives for the same. Continuous loop tape cartridge player systems are well known in the art. Basically, the cartridge is comprised of a hub, a platen, a pressure roller, and guiding means to guide a continuous loop of tape. The tape is wound about the hub and guided past a front access and around the pressure roller. The tape player is provided with a vertically standing capstan which is rotatably driven off a motor actuated flywheel. The capstan is located such that on cartridge insertion into the player the capstan forcibly engages the pressure roller thus rotatably driving the roller. The tape, being pinched between the pressure roller and capstan, is thereby driven.
Until recently, the popularity of cartridge tape players was retarded due to a serious limitation. Namely, the player could only drive the tape at a single speed. Thus, for example, if it were desired to hear a track that had just been played, the user would have to wait until the tape played through at its normal playing speed. To overcome this problem some manufacturers provided a means whereby the player motor speed was increased. This proved unsatisfactory, however, since motor life was significantly degraded. An excellent solution to the problem is offered by Melvin Lace in his application Ser. No. 563,947, filed Mar. 31, 1975, now abandoned, and assigned to the same assignee as the instant invention. Lace teaches a means whereby the effective diameter of the capstan is increased in the fast forward mode. A pair of predeterminedly developed crescents ride on the capstan, and allow capstan-pressure roller interface in the normal play mode. On activation to fast forward, the upper crescent clutches to the capstan for rotation therewith. The upper crescent rotates 180.degree. out of phase with the lower crescent at which time rotational drive from the upper crescent is coupled to the lower crescent via a pin and trough arrangement. The crescent outer surfaces interface with the pressure roller effecting fast forward.
It has been found, however, that the above mentioned fast forward mechanism is subject to an occasional problem. When the player returns from the fast forward to the normal play speed, the upper crescent indexes and declutches at a point at which the lower crescent is still in contact with the pressure roller. Since the lower crescent had been primarily driven by the upper crescent, it loses a significant rotational force which would tend to index it back in the normal play mode. Occasionally, especially with rubber pressure rollers, the remaining rotational forces on the lower crescent are not sufficient to index it properly, resulting in an undesirable player "hang up."